1. Field of the Invention
The present invention relates to a network managing method and system for maintaining and managing an ATM (Asynchronous Transfer Mode) network.
2. Description of the Related Art
Recently, a variety of demands for information communications have been increasing, and not only data of conventional speech communications but also data such as image data etc. are required to be exchanged between users. Especially, a communications network must quickly transmit a large amount of information for a video telephone which exchanges moving images, etc. in real time. If a communications network accommodating such a video telephone only is separately arranged, it must be juxtaposed with a conventional telephone network, etc. Therefore, it is difficult to maintain such networks. As a result, there is a demand for a high-speed communications network where image data communications, etc. as well as conventional speech communications can be implemented. An analog line switching network such as a conventional telephone network, etc. is difficult to adopt as such a communications network, and a communications network implemented with a new method is required. An ATM communications network (ATM network) has been actively studied and developed as the most promising technique of such a communications network.
In the ATM communications network, information of voice, images, etc. are resolved into packets referred to as fixed-length cells, to each of which a VPI/VCI, that is, an address for a cell switching process, is assigned, and the cell is routed accordingly. In such an ATM communications network, user terminals are interconnected via communications lines arranged between ATM exchanges. The specification of an ATM exchange is standardized based on the recommendations of the ITU-T. Common carriers are currently developing ATM communications networks, conforming to these recommendations. The capabilities to be included in an ATM exchange, which is an important constituent element of an ATM communications network, are stipulated by the standardized recommendations. The typical configuration of the ATM exchange comprises a line corresponding unit for terminating a transmission line, an ATM switch for routing cells, and a process or for controlling all of the operations of the ATM exchange.
For an exchange configuring a network, a maintenance terminal for maintaining and managing the exchange itself is normally arranged. However, a centralized management center maintains and manages an entire network including exchanges. Therefore, the scale of the centralized management center becomes larger with the increase of the scale of the network. There is a demand for saving the cost of such maintenance and management of the network.
FIG. 1 is a block diagram for explaining the configuration of a conventional ATM network. 100 indicate exchanges. 101 indicates a centralized management center. 102 indicates an ATM switch. 103 and 104 indicate line corresponding units. 105 indicates a controlling unit. 106 indicates a maintenance terminal. The exchanges 100 have almost the same configuration where ATM cells are transmitted/received by the line corresponding units 103 and 104 and are routed by the ATM switch 102. A network is configured by interconnecting such exchanges 100 with lines.
The centralized management center 101 has the capability for maintaining and managing the network by collecting the information of the respective exchanges 100. The maintenance terminal 106 has the capability for maintaining and managing a local exchange, and the capability for transmitting/receiving information to/from the centralized management center 101 depending on need. However, the maintenance terminal 106 does not have the capability for maintaining and managing other exchanges.
An ATM cell transmitted over an ATM network has a 53-byte configuration composed of a 5-byte header and a 48-byte information field. ATM cells are classified into two major categories: a user cell and an OAM (Operation, Administration, and Maintenance) cell. The user cell transmits speech, images, data, etc. between subscribers using the information field. The OAM cell has a capability for monitoring performance, a capability for detecting a fault/problem, a capability for protecting a system, a capability for transmitting fault information/performance report information, a capability for identifying a location where a fault has occurred, etc. The OAM cell is transmitted by being inserted into an empty position of the user cell.
Typically, each of the exchanges 100 comprises the maintenance terminal 106, which has the capability for maintaining and managing a local exchange as described above. For example, the maintenance terminal 106 can establish/release a PVC (Permanent Virtual Channel) between an opposing exchange and a local exchange, and can read path information, etc. However, it does not have a capability for performing various control operations for other exchanges.
Accordingly, when a network fault occurs, the normality of a local exchange can be verified, but that of other exchanges 100 cannot be verified. Therefore, the centralized management center 101 isolates the location where a fault has occurred, and sets up a bypass, so that it becomes difficult to quickly recover from the fault.
The operations of an ATM exchange are controlled by a processor. When an ATM communications network is upgraded, the processes performed by the ATM exchange may sometimes be desired to be changed. In this case, the file or files including the program or software for running the processor must be updated.
Conventionally, a maintenance engineer visits all of the stations (including exchanges), which configure an ATM network, and loads a new file from the medium storing the new file into the processor of the exchange with the entry of a command, etc.
Additionally, the system version of each of the stations is read by the centralized management center, or that of an exchange is read by the maintenance engineer of each of the stations (with the entry of a command, etc.), in order to manage the version number of each of the stations.
Furthermore, the centralized management center stores the version number of each of the stations in a database.
As the number of constituent elements configuring an ATM network increases, the size of the database for managing version numbers become larger. As a result, a lot of system resources become necessary. Furthermore, a maintenance engineer must visit each station and perform the operation for updating each file at each station. Consequently, a considerable amount of labor is required to update files or databases.
An object of the present invention is to make a maintenance terminal included in an exchange perform the operations such as maintenance, management, etc. for another exchange or other exchanges with a relatively simple means.
A further object of the present invention is to provide a means for facilitating an update of a file of each ATM exchange in an ATM network, and for allowing management to be performed.
A network managing method according to the present invention is a method with which one exchange specifies, maintains, and manages another exchange in a network. This method comprises the steps of: transmitting an order for maintaining and managing an exchange at an order request destination by specifying this exchange from an exchange at an order request source, by using a control cell; and executing the order included in the control cell in the exchange at the order request destination which receives the control cell. Namely, this method allows the maintenance and management of another exchange by transmitting the order with the control cell.
The control cell is composed of a header and an information field. The information field includes a request identifier indicating the contents of an order, a sequence number when the order is divided and transmitted, and a total number indicating the number of divisions. Accordingly, a simple order may sometimes require only a single cell, whereas a complicated order requires a plurality of cells to be transmitted, into which the order is divided.
Additionally, the exchange at the order request destination sets the permission/prohibition of the execution of the order in a table, makes a comparison between the contents of the order included in the control cell and those of the table. The order can be executed only if the execution is permitted for the order from the exchange at the order request source.
Furthermore, the exchange at the order request destination may return to the exchange at the order request source the result of the execution of the order from the exchange at the order request source, and may make the maintenance terminal of the exchange itself display the contents of the order and the result of the execution of the order.
A network managing system according to the present invention is a managing system for maintaining and managing a network where a plurality of exchanges are interconnected. An exchange at an order request source includes a maintenance terminal for specifying an exchange at an order request destination and for inputting an order; a controlling unit for editing the order with the order input from the maintenance terminal, and for controlling respective units; line corresponding units for storing the order in the information field of a control cell and for transmitting the order according to an instruction from the controlling unit; and an ATM switch for routing an ATM cell. An exchange at an order request destination includes line corresponding units for receiving and identifying the control cell which is transmitted from the exchange at the order request source and is addressed to the local exchange itself, and for extracting the order stored in the control cell; a controlling unit for performing control according to the order extracted by the line corresponding units; and an ATM switch for routing an ATM cell.
Each of the line corresponding units included in the exchange at the order request source assigns a sequence number indicating a transmission order and a total number indicating the number of divisions, to each of control cells when the order is divided and transmitted. In the meantime, the line corresponding unit included in the exchange at the order request destination determines whether or not the reception of the order is completed, according to the sequence number and the total number of the received control cell, and transfers the order to the controlling unit.
Furthermore, the exchange at the order request destination may include a table for setting the permission/prohibition of the execution of the order transmitted from the exchange at the order request source. The controlling unit may determine whether the received order is either permitted or prohibited by referencing the table, and may execute the order only if the order is determined to be permitted.
Each of the line corresponding units included in the exchange at the order request destination returns to the exchange at the order request source the result of the execution of the order transmitted from the exchange at the order request source, under the control of the controlling unit. This unit may include a maintenance terminal for displaying the contents of the order and the result of the execution under the control of the controlling unit.
Furthermore, a method according to the present invention is a method for updating-a file stored by a station on a VP/VC link in an ATM network. This method comprises the steps of: defining a control cell in the ATM network as a first control cell for checking the version number of the file stored at the station on the VP/VC link; transmitting the first control cell to the station over the VP/VC link; and obtaining the version number of the file stored at the station to which the first control cell is transmitted, from the response made to the first control cell transmitted to the station.
In this way, it is unnecessary to manage a huge amount of data for managing the version numbers of the files stored at respective stations on a VP/VC link in a single database, thereby reducing the resources used for managing a network.
Furthermore, the method according to the present invention may further comprise the steps of: defining a control cell in the ATM network as a second control cell for requesting the station on the VP/VC link to start the preparation of a file update operation; transmitting the second control cell to a station whose file must be updated; and starting the file update operation according to the response from the station whose file must be updated.
As described above, the start of the file update operation can be instructed to each station with control cells, whereby a maintenance engineer need not trouble to visit each station and perform the file update operation.
The method according to the present invention may further comprise the steps of: defining a control cell in the ATM network as a third control cell for carrying a new file required for an update to the station over the VP/VC link; and dividing the new file required for the update into third control cells, storing the new file in the third control cells, and transmitting the third control cells to the station whose file must be updated. Therefore, a maintenance engineer no longer needs to save the new file onto a storage medium such as a CD-ROM, etc., to carry the storage medium to each station, and to manually perform the file update operation, thereby facilitating the maintenance and management.
Here, the control cell refers to a cell for managing the network, particularly, to the OAM cell.